1. Field of the Invention
This invention relates to semiconductor device manufacturing apparatus and, more particularly, to a semiconductor device manufacture apparatus for rapid thermal chemical vapor deposition (RTCVD) utilizing a short-time heat treatment.
2. Description of the Related Art
FIG. 3 is a schematic cross-sectional view of a conventional semiconductor manufacturing apparatus, e.g., an RTCVD apparatus. A semiconductor wafer 2 is accommodated in a process chamber 1 and supported by a susceptor 3. A door 4 for introduction of a semiconductor wafer is provided at an end of the process chamber 1, and a process gas introduction port 5 and a discharge port 6 are provided at the other end. Tungsten halogen lamps 7 for heating the semiconductor wafer 2 and apyrometer 8 for measuring the temperature of the semiconductor wafer 2 are provided at the periphery of the process chamber 1.
The thus-constructed conventional semiconductor device manufacturing apparatus is used as described below. First, the door 4 is opened, semiconductor wafer 2 is introduced into the process chamber 1 and is placed on the susceptor 3, and the door 4 is thereafter closed. Next, the interior of the process chamber 1 is evacuated through the discharge port 6, and a desired process gas is introduced into the process chamber 1 through the process gas introduction port 5. After a predetermined gas flow rate and a predetermined pressure have been reached and stably maintained, the tungsten halogen lamps 7 are energized to heat the semiconductor wafer 2. Then, the temperature of the semiconductor wafer 2 is monitored by the pyrometer 8, and RTCVD is effected at the set temperature for the set time.
This semiconductor device manufacturing apparatus entails problems described below. The first problem is temperature measurement. To measure the temperature with accuracy by using the pyrometer 8, it is necessary to know the emissivity of the wafer 2 at the measurement wavelengths at the measured surface, i.e., the reverse surface of the semiconductor wafer 2 in this case. This emissivity is a sensitive function of the condition of the reverse surface of the semiconductor wafer 2. For example, in the conventional RTCVD apparatus, the emissivity at the reverse surface of the semiconductor wafer 2 changes with time because a layer is also deposited on this surface. It is therefore impossible to monitor the temperature with the pyrometer 8.
Second, at least part of the process chamber 1 is made of a material capable of transmitting infrared rays, e.g., quartz as a window, since the tungsten halogen lamps 7 are used for the light source to heat the semiconductor wafer 2 with infrared rays. Since such a window material does not completely transmit infrared rays, the window member itself is also heated up, and the temperature thereof is increased. Therefore a layer is also deposited on the window member, so that the infrared ray transmissivity is reduced. A vicious cycle thereby arises; the temperature of the window member is further increased and the layer deposition proceeds. Ultimately, infrared rays cannot reach the semiconductor wafer 2 which is to be heated.